Buggy code:
public final class Specification { private static final String MISSING = "Missing<seq2seq4repair_space>" ; public static final Attributes . Name SPECIFICATION_TITLE = Attributes . Name . SPECIFICATION_TITLE ; public static final Attributes . Name SPECIFICATION_VERSION = Attributes . Name . SPECIFICATION_VERSION ; public static final Attributes . Name SPECIFICATION_VENDOR = Attributes . Name . SPECIFICATION_VENDOR ; public static final Attributes . Name IMPLEMENTATION_TITLE = Attributes . Name . IMPLEMENTATION_TITLE ; public static final Attributes . Name IMPLEMENTATION_VERSION = Attributes . Name . IMPLEMENTATION_VERSION ; public static final Attributes . Name IMPLEMENTATION_VENDOR = Attributes . Name . IMPLEMENTATION_VENDOR ; public static final Compatibility COMPATIBLE = new Compatibility ( "COMPATIBLE" ) ; public static final Compatibility REQUIRE_SPECIFICATION_UPGRADE = new Compatibility ( "REQUIRE_SPECIFICATION_UPGRADE" ) ; public static final Compatibility REQUIRE_VENDOR_SWITCH = new Compatibility ( "REQUIRE_VENDOR_SWITCH" ) ; public static final Compatibility REQUIRE_IMPLEMENTATION_CHANGE = new Compatibility ( "REQUIRE_IMPLEMENTATION_CHANGE" ) ; public static final Compatibility INCOMPATIBLE = new Compatibility ( "INCOMPATIBLE" ) ; private String specificationTitle ; private DeweyDecimal specificationVersion ; private String specificationVendor ; private String implementationTitle ; private String implementationVendor ; private String implementationVersion ; private String [ ] sections ; public static Specification [ ] getSpecifications ( final Manifest manifest ) throws ParseException { } public Specification ( final String specificationTitle , final String specificationVersion , final String specificationVendor , final String implementationTitle , final String implementationVersion , final String implementationVendor ) { } public Specification ( final String specificationTitle , final String specificationVersion , final String specificationVendor , final String implementationTitle , final String implementationVersion , final String implementationVendor , final String [ ] sections ) { } public String getSpecificationTitle ( ) { } public String getSpecificationVendor ( ) { } public String getImplementationTitle ( ) { } public DeweyDecimal getSpecificationVersion ( ) { } public String getImplementationVendor ( ) { } public String getImplementationVersion ( ) { } public String [ ] getSections ( ) { } public Compatibility getCompatibilityWith ( final Specification other ) { } public boolean isCompatibleWith ( final Specification other ) { } public String toString ( ) { } private boolean isCompatible ( final DeweyDecimal first , final DeweyDecimal second ) { } private static ArrayList removeDuplicates ( final ArrayList list ) { final ArrayList results = new ArrayList ( ) ; final ArrayList sections = new ArrayList ( ) ; while ( ( list . size ( ) ) > 0 ) { final Specification specification = ( ( Specification ) ( list . remove ( 0 ) ) ) ; final Iterator iterator = list . iterator ( ) ; while ( iterator . hasNext ( ) ) { final Specification other = ( ( Specification ) ( iterator . next ( ) ) ) ; if ( Specification . isEqual ( specification , other ) ) { final String [ ] otherSections = other . getSections ( ) ; <START_BUG> if ( null != sections ) { <END_BUG> sections . addAll ( Arrays . asList ( otherSections ) ) ; } iterator . remove ( ) ; } } final Specification merged = Specification . mergeInSections ( specification , sections ) ; results . add ( merged ) ; sections . clear ( ) ; } return results ; } private static boolean isEqual ( final Specification specification , final Specification other ) { } private static Specification mergeInSections ( final Specification specification , final ArrayList sectionsToAdd ) { } private static String getTrimmedString ( final String value ) { } private static Specification getSpecification ( final String section , final Attributes attributes ) throws ParseException { } }

Fix:
if ( null != otherSections ) {